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Work experience

Senior Java Developer

from 09.2023 to now (1 year 11 months)
Luxoft, Дистанційно (IT)

Project description:
A large project whose purpose was to facilitate trading in financial markets.

Achievements:
•Designed and implemented custom module to handle securities trading of following types: receive free, delivery free, receive versus payment, deliver versus payment using Spring Integration and EMS and IBMMQ. Optimized the module using caching connection factory.
•Made sure processing is concurrent using @Async and thread pool for task execution inside the integration flow.
•Utilized RxJava and WebFlux for reactive programming to manage asynchronous and event-based processes
•Implemented integration testing pipeline for new module.
•Implemented performance testing pipeline that tested the module with different types of garbage collections and memory heap sizes to ensure low latency and best performance.
•Profiled application during runtime to ensure no memory leaks present.
•Designed a robust message queue data structure to ensure efficient and ordered transaction processing in high-frequency trading scenarios.

Responsibilities:
•Developed and maintained Java applications, bugfixing, participating in daily scrum meetings

Development tools:
•IntelliJ-Idea. Gradle, IoC/DI, Java 8, JDBC/Hibernate/JPA, Spring Integration, IBMMQ, TIBEMS, REST, Git, Gitlab, Autosys.

Senior Java Developer

from 10.2019 to 09.2023 (3 years 11 months)
GlobalLogic Ukraine, Дистанційно (IT)

Project description:

A large project whose purpose was to implement ETL data pipelines for data integration needs.

Achievements:
•Implemented rest endpoints for data pipelines: java core transformations, writing to db’s, file systems.
•Leveraging java 8 parallel stream api to implement data transformations; ensured camel’s parallel processing of a route; implemented multiple listener generation for SQS.
•Designed and implemented code generation strategy based on templates.
•Fixed difficult issues in data transformation with the help of Java Core. Found 1 bug in maven meanwhile!
•Fixed issues in CXF, Camel code. SQS. SQS module didn’t have any means to define durable subscription.
•Testing deployments on AWS, Azure and GCP.
•Received recognition for exceptional customer support, resulting in a long-term partnership with the client and new project opportunities.
•Designed and implemented complex data transformation structures that maintained data integrity across multiple systems.
•Designed an optimized data structure for batch processing to handle large datasets, allowing for parallelized processing and minimal memory footprint.
•Profiling customer routes which misbehaved.

Responsibilities:
•Developed and maintained Java applications, bugfixing, participating in daily scrum meetings.

Development Tools:
•Eclipse, IntelliJ-Idea, ESB, WSO2, Java 8 – 11, Eclipse RCP, Mulesoft, Talend, JDBC/Hibernate/JPA, Kafka/ActiveMQ, Spring Boot, Angular, React, JaxB/Jackson, CXF, Jersey, Apache Camel, Angular, JET, REST/SOAP, gRPC, Tomcat, Netty, AWS (SQS, S3, EC2), Azure, GCP, Git., Jenkins., Jira, Postman, Scrum.

Senior Java Developer

from 11.2018 to 10.2019 (11 months)
SoftServe, Київ (IT)

Project description:
I was in charge of a large microservice project that was intended to provide a web internet security solution for various firms. The project provided customers with web antivirus tools, website trust score tools, log analyzer tools, and firewall tools that allowed the customer to monitor the usage of the internet traffic in their account. Extensive knowledge of security principles was required. Around 11000 distributed microservice instances were operating to support the traffic that came from customers.

Responsibilities:
•Optimized connection establishment which relaxes security requirement if user has old software and uses most secure cipher suite for eligible software clients.
•Designed a custom scanner which scans URLS on a page (safe search)
•Optimized threat scanning and security checks using concurrency api to speed up scanning pipeline.
•Utilizing JVisualVM to find memory leak related to open but never closed connection; application profiling.
•Implementation of rest services, business logic in spring, scala.
•Designed data structure to implement exe file scanning.
•Fixing issues: security, core, etcs.
•Administration of servers and deployments on Mesos/Marathon.
•Used data structures to represent and scan executable files efficiently, ensuring that large files were processed in parallel and without excessive memory usage.
•Designed data structures for network traffic logs to efficiently process large volumes of web traffic data while minimizing latency.
•Monitoring Vertica -> Kafka -> ELK pipeline, adding Spark like this: Vertica -> Kafka -> Spark -> ELK. Wring Spark streaming processor to show and analyze real time traffic events across whole microservices.
•Developed efficient graph structures to represent and analyze security threats in web traffic, allowing for optimized querying and analysis.

Achivements:
Eclipse, Intellij Idea, Java 8 - 11 / Scala, JavaScript, HTML, CSS, React, Spring/Spring Boot, IoC/DI, Spring Cloud, Hibernate/JPA/JDBC, gRPC, Kafka/Zookeeper, ElasticSearch/Kibana, SAML/SSO, Spark, Swagger/Open API, AWS (Route53, S3, EC2), Bare-Metal Servers, CentOS, Vertica, CouchBase, PostgreSQL, Apache Mesos, Kubernetes/Terraform, Docker, Etcd, Consul, Puppet, KeyCloak, Gatling, JMeter, Grafana, Gerrit, Postman, AWS Serverless.

Senior Java Developer

from 04.2016 to 09.2018 (2 years 5 months)
EPAM, Київ (IT)

Project description:

Large enterprise stream of projects intended to implement the functioning of an insurance company. The project idea was to migrate it to microservice architecture (to 100+ microservices) and it consists of 4 parts. First is a highly responsive workflow dispatch application that allows managing administrative approvals between different company departments; a Smart Forecasting engine that provides estimation-based decisions for each type of client, Cloud Management Application that provides professional monitoring and scalability services with alarms that integrate with Jira and pager duty; Management view application which implements 100+ views for different types of tasks. The project builds on many modern Java approaches; it supports many users.



Responsibilities:

Mentoring junior team members;
Handling customer inquiries;
Updating business rules;
Participating in meetings with clients;
Participating in team review activities;
Coordinating team activities;
Ensuring effective communication across cross-functional departments;
Participating in technical training;
Participating in knowledge transfer sessions;
Software migration;
Administration of servers;
Programming Languages: Java, SQL, Javascript

Markup language: HTML, CSS

Frameworks:

Zk, Mybatis/JDBC, Log4J, JUnit/Mockito/Easymock, Activity BPM, JSON/XML.

API's: REST/SOAP

Build tool: Maven

APIs: Java Concurrent API

DB: Oracle, H2

Operating system: RedHat

Application container: JBoss, Jetty

Administration tool: Syslog

C/C++ Developer

from 04.2015 to 09.2017 (2 years 5 months)
Waves Shop, Київ (IT)

Project intended to optimize quality of audio on mobile devices: MaxxBass, MaxxTreble, MaxxVolume, Stereo imaging modules, stable volume module. I optimized modules for Arm and Ceva arthitectures with a focus on a performance.

Responsibilities:
•Participare in scrum meetings
Achivements:
•Tuned compiler flags for maximum performance.
•Profiled modules using gperf, VTune and perf. Calculates MIPS using perf counters.
•Wrote a module that calculates MPS of the audio modules.
•Vectorizing algorithms using parallel processing instructions (SIMD).
•Optimizing memory usage on a register level
•Using ASM for better utilization of CPU registers, rewriting instructions order based on it’s throughput and latency, accounting on data size and size of L1, L2, L3 cache lines, writing code accounting for out of order execution.
•Writing memory compressor engine to save memory footprint of presets in a preset management software using LZ77 and LZ78 algorithms.
•Writing a java wrapper that would call optimized functions which set presets from Java phone app.

Tools: C++, gcc, g++, CMAKE, make, visual studio, vim, gprof, perf, VTune, SIMD, Linux.

Qt/Q++ Developer

from 06.2013 to 04.2015 (1 year 10 months)
GlobalLogic Ukraine, Львів (IT)

Project description:
The goal of the project was to develop software to show human vitals on a defibrillator on a UI using QT.

Achievements:
•Developed a module according to a speficication.
•Collaborated with the UI/UX team to revamp the user interface, resulting in a modern and visually appealing design that increased user engagement.

Responsibilities:
•Participating in SCRUM meetings;
•Implementing new UI features;
•Learning new things and consulting with the team lead;
•Creating a roadmap for self-development;
•Bug fixing;

Programming Language: C++, QT
Development IDE: Qt Creator
Source control: git
Team collaboration tool: Jira

Education

National University "Lviv Polytechnic"

Software Engeneering, Sambir
Higher, from 2009 to 2014 (5 years)

Knowledge and skills

• Самостійність

Language proficiencies

English — above average